[Python-Dev] Every Release Can Be a Mini "Python 4000", Within Reason (was (name := expression) doesn't fit the narrative of PEP 20)

[Jeff Allen]

On 27/04/2018 08:38, Greg Ewing wrote:
> How would you complete the following sentence? "The ':='
> symbol is a much better symbol for assignment than '=',
> because..."
>
... users new to programming but with a scientific background expect '=' 
to be a statement of an algebraic relationship between mathematical 
quantities, not an instruction to the machine to do something.

That's easy to answer.  (I can remember this particular light bulb 
moment in a fellow student, who had been using a different name in every 
assignment statement, and had found loops impossible to understand.) 
Also it frees up '=' to be used with something like its expected meaning 
in conditional statements, without making parsing hard/impossible. There 
are arguments the other way, like brevity and familiarity to other 
constituencies. But I feel we all know this.

Having chosen to go the '=', '==' route, the cost is large to change, 
especially to get the other half of the benefit ('=' as a predicate). So 
I think the question might be who is it better for and how much do we care.

And whether the days are gone when anyone learns algebra before programming.

I speculate this all goes back to some pre-iteration version of FORmula 
TRANslation, where to its inventors '=' was definition and these really 
were "statements" in the normal sense of stating a truth.

Jeff Allen

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